a) 271 × 275 = 271 × (273 + 2) = 271 × 273 + 271 × 2
273 × 273 = (271 + 2) × 273 = 271 × 273 + 2 × 273
Vì 271 × 2 < 2 × 273
=> 271 × 275 < 273 × 273
b) 569 × 564 = (567 + 2) × 564 = 567 × 564 + 2 × 564
567 × 566 = 567 × (564 + 2) = 567 × 564 + 567 × 2
Vì 2 × 564 < 567 × 2
=> 569 × 564 < 567 × 566
a) 271 × 275 = 271 × (273 + 2) = 271 × 273 + 271 × 2
273 × 273 = (271 + 2) × 273 = 271 × 273 + 2 × 273
Vì 271 × 2 < 2 × 273
=> 271 × 275 < 273 × 273
b) 569 × 564 = (567 + 2) × 564 = 567 × 564 + 2 × 564
567 × 566 = 567 × (564 + 2) = 567 × 564 + 567 × 2
Vì 2 × 564 < 567 × 2
=> 569 × 564 < 567 × 566
a) 271 × 275 = 271 × (273 + 2) = 271 × 273 + 271 × 2
273 × 273 = (271 + 2) × 273 = 271 × 273 + 2 × 273
Vì 271 × 2 < 2 × 273
=> 271 × 275 < 273 × 273
b) 569 × 564 = (567 + 2) × 564 = 567 × 564 + 2 × 564
567 × 566 = 567 × (564 + 2) = 567 × 564 + 567 × 2
Vì 2 × 564 < 567 × 2
=> 569 × 564 < 567 × 566
a) 271 × 275 = 271 × (273 + 2) = 271 × 273 + 271 × 2
273 × 273 = (271 + 2) × 273 = 271 × 273 + 2 × 273
Vì 271 × 2 < 2 × 273
=> 271 × 275 < 273 × 273
b) 569 × 564 = (567 + 2) × 564 = 567 × 564 + 2 × 564
567 × 566 = 567 × (564 + 2) = 567 × 564 + 567 × 2
Vì 2 × 564 < 567 × 2
=> 569 × 564 < 567 × 566